The relationship between local and regional extinction rates depends on species distribution patterns

The rapid loss of biodiversity poses a great threat to ecosystem functions and services. Credible estimation of species extinction rates is essential for understanding the magnitude of biodiversity loss and for informing conservation, but this has been a challenge because estimated extinctions are unverifiable due to the lack of data. In this study, we investigated the relationship between local and regional extinctions and assessed the effects of range size, spatial segregation and patchiness of species distribution on this local–regional extinction relationship. We found that regional extinction rates had a convex relationship with local extinction rates, that is, the regional extinction rate was most likely to be lower than the average local rate. The regional rates deviated from local rates as the sampling area decreased. The difference between local and regional extinction rates (local–regional extinction difference) became larger if a higher number of species had larger range sizes and patchiness. We also detected that there were interactive effects among these factors. Species segregation had a weak positive relationship with the local–regional extinction difference if more species had relatively large range sizes. As the sampling areas increased, the range size showed smaller positive effects on local–regional differences, but patchiness showed larger positive effects. The local–regional extinction relationship of this study provides insights into the spatial scaling of biodiversity loss and offers some important cues for estimating regional extinctions from local data in future studies.